Riddick, 23, is a former fifth-round pick of the Cardinals back in 2015. He lasted just over a year in Arizona before he was waived coming out of the preseason.
Arizona later signed Riddick to their practice squad before cutting him loose a few weeks ago.
During his senior year at West Virginia, Riddick recorded 25 tackles, nine tackles for a loss and six sacks over the course of nine games.
Thompson, 23, signed on with the Texans as an undrafted free agent out of Mississippi back in May of last year. He managed to make the 53-man roster during his rookie season but spent most of the year on the team’s injured reserve list.
The Texans elected to cut Thompson loose coming out of the preseason.
In 2015, Thompson appeared in two games and recorded two tackles for the Texans.